Borehole logging signaling system



Nov. 4, 1958 E. w. PETERSON BOREHOLE LOGGING sxcmmmc SYSTEM 4Sheets-Sheet 1 fir 6.61

INVENTOR, tE'Zlfl/A/(d #275950 Filed March 1, 1954 Nov. 4, 1958 E. w.PETERSON BOREHOLE LOGGING SIGNALING SYSTEM 4 Sheets-Sheet 2 Filed March1, 1954 INVENTOR Nov. 4, 1958 E. w. PETERSON BOREHOLE LOGGINGSIGNALINGSYSTEM 4 Sheets-Sheet 3 Filed March 1, 1954' 4 Jim T '7 0. w .m a Q m V1 1 C k 0 0N0M M I 0 0 0 0 0 0 0 0 0 0 0 0 0 Nov. 4, 1958 E. w. PETERSONBOREHOLE LOGGING SIGNALING SYSTEM 4 Sheets-Sheet 4 Filed March 1, 1954INVENTOR fldflffi/ [a #522230 BY 1 p M I United States Patent BOREHGLELOGGING SIGNALING SYSTEM Elwin W. Peterson, Pasadena, Calif., assignor,by mesne assignments, to Dresser Industries, Inc., Dallas, Tex., acorporation of Delaware Application March 1, 1954, Serial No. 413,397

11 Claims. (Cl. 255-1) The invention hereinafter disclosed relates ingeneral to earth borehole logging systems of the type wherein signalsrepresentative of desired information such as various physical quantitymeasurements obtained by one or more measurement devices within a wellborehole may be transmitted to a point outside the borehole forrecording, analysis, or other purposes during and without interruptionof the drilling operation.

More particularly, the invention relates to improvements in thebefore-mentioned type of borehole logging systems, whereby the stream ofdrilling fluid normally pumped downwardly under pressure through theinterior of a hollow drill string is, in addition to being employed asthe transmission medium serving to transmit measurement-representingsignals to the top of the borehole, also employed in a novel manner toenergize the signal-producing means within the borehole.

Borehole logging systems adapted for logging while drilling and whichhave utilized energy derived from the moving drilling fluid as a sourceof power at the bottom of the borehole have, because of the relativelylarge power requirements of the kind of apparatus heretofore used,required for such purpose impellers, turbines, and the like devices, therotors of which were situated in the drilling fluid stream and werecoupled to drive either an electric generator or a complicatedarrangement of mechanical parts which were in turn utilized to furnishpower to the measurement and signal-producing devices. These systemssuffered the obvious disadvantages of requiring at least one rotatingshaft or member extending from within a relatively protected enclosurethrough a seal and into the stream of abrasive drilling fluid, and fromhaving a relatively large number of somewhat complicated and delicatemoving parts located in an environment of severe mechanical vibrationand shock. Also, large drilling cuttings or chips or other solidmaterial carried by the circulating drilling fluid were apt to clog ordamage such turbine and impeller devices and thereby interrupt theproper operation of the apparatus.

With the previously noted and other evident disadvantages of prior artborehole logging systems in view, it is an important object of thepresent invention to provide in a borehole logging System a simple meansdirectly utilizing a portion of the pressure gradient along the drilling fluid stream to move a flow-changing means into flowchangingrelationship with the drilling fluid stream, whereby a signalingflow-change or pressure-change is produced in the drilling fluid.

Another object of the invention is to provide a system of the typebefore-mentioned comprising a simple flowchanging device which cannot bechoked by drill cuttings.

Another object of the invention is to provide a system for boreholelogging while drilling comprising a simple means utilizing kineticenergy of the drilling fluid stream to produce one or more signalingpressure-changes in the drilling fluid stream.

Another object of the invention is to provide a simple drilling fluidflow-restricting device which, when flow restricting movement thereof isinitiated, becomes largely self-energizing, and requires only arelatively small amount of energy to initiate and control such action ofthe device.

An additional object of the invention is to provide simple meansutilizing directly a portion of the energy of a drilling fluid stream tomove a drilling fluid flow-changing means into flow-changing attitude orrelationship with the drilling fluid stream.

A still further object of the invention is to provide a system of wellborehole logging in which energy possessed by the drilling fluid streamis directly utilized by simple means to produce a pressure-change signalin the drilling fluid stream.

Broadly, the present invention resides in a novel apparatus and methodby which useful information obtained by suitable instrumentalitieswithin a borehole may be transmitted to the surface of the earth by asignal in the form of changes in character of flow of the drillingfluid, such changes preferably being in the form of a plurality ofrepetitive pressure-changes in the drilling fluid stream in the drillstring, either during drilling or between drilling periods, or both,utilizing the normal pressure gradient in a portion of the drillingfluid stream to supply substantially all of the energy required forinitiating and producing such pressure changes. More specifically, thepressure in the drilling fluid stream is, by suitable means, picked upor sensed at a first point and transmitted or translated to a flexiblemember positioned to vary the resistance to flow of the fluid stream atanother point, there preferably being a pressure differential in thestream between the two points, due to the mentioned pressure gradient,to cause the flexible member to be flexed into the stream to increasethe resistance to flow thereof or flexed out of the stream to decreasethe resistance to flow thereof, thereby producing -pressure-changesignals in the stream. Since substantially all of the energy required toproduce the drilling fluid pressure-change signals may thus be deriveddirectly from the drilling fluid stream, and may be directly utilizedWithout conversion to another form of energy, the turbogenerator orrotary means heretofore employed may be dispensed with; with theremaining requirement only that an actuating or triggering means ofsmall size and requiring only an extremely small amount of energy forits operation be employedfor initiating and controlling the action ofthe signaling apparatus.

The hereinhefore mentioned and other objects, advan vantages, andfeatures of novelty will become evident hereinafter wherein a preferredembodiment of apparatus and best mode contemplated for carrying out theinvention are described in conjunction with the drawings, in which likereference characters designate the same or similar parts throughout theseveral views, and in which:

Figure l is a view, partly in elevation and partly in longitudinalsection, illustrating a typical drilling rig and an earth boreholeproduced thereby, and including a general arrangement and location ofthe apparatus of the invention;

Figure 2a is an enlarged longitudinal view, partly in section, of a partof the apparatus shown in Figure 1;

Figure 2b is an enlarged longitudinal view, partly in section, of a partof the apparatus shown in Figure 1 and forming an extension of thestructure depicted in Figure 2a;

Figure 3a is a longitudinal sectional view, partly diagrammaticillustrating a portion of the hydraulic fluid connections and apparatusof Figures 2a and 2b, and showing the position of certain of theapparatus elements at one stage of a signaling cycle;

Figure 3b is a fragmentary view of apparatus shown in Figure 3a andillustrating the position of certain of the apparatus elements atanother stage of the signaling cycle;

Figure 4 is a transverse sectional view of a modified form of valvestructure;

Figure 5a is a transverse sectional view of the modified form of thevalve structure of Figure 4;

Figure 5b is a transverse sectional view of the apparatus of Figure 5ashowing the valve means in drilling fluid flow-restricting position;

Figure 6 is a transverse sectional view of a second modified form of thevalve structure;

Figure 7a is a transverse sectional view of the second modified form ofthe valve structure;

Figure 7b is a transverse sectional view of the apparatus of Figure 7ashowing the valve means in flowrestricting attitude.

Referring now to the drawings, and more specifically to Figure 1, thereis shown a typical well borehole 2 formed by a conventional rotarydrilling method through successive strata 4, 6, 8, 10 and 12 of theearth, the upper portion of the borehole being lined with a conventionalsurface casing 14 cemented in as shown at 16. Suspended within theborehole is a drill string including a bit 18, a drill collar 20connecting the bit to one or more sections of drill pipe 22, and a Kellybar 24 arranged to rotate the drill pipe, and which in turn is supportedfor rotation by a swivel 26 carried by a travelling block 28 of aconventional drilling rig. The rig comprises a conventional derrick 30,a power unit or draw-works 32, a rotary table including bevel gearing33, for gripping and rotating the Kelly bar, and a drilling fluid pump34. The pump has an intake 35 extending into and receiving drillingfluid from a sump 36 and a discharge through a surge chamber to a pipe38 through which the drilling fluid is delivered under pressure to theinterior of the derrick and thence to the drill string by way of aflexible rotary hose 39 and the before-mentioned swivel 26. Theapparatus thus far enumerated, with the exception of drill collar 20,may be of conventional design and are shown to illustrate theenvironment of the instant invention and to aid in a clear explanationof the operation of the system of the invention. The drilling fluidreceived by pump 34 from sump 36 through intake 35 is forced into pipe38 past or through surge chamber 37, which acts to greatly decrease therelatively high frequency fluctuations in pressure in pipe 38 resultingfrom the inherent delivery characteristics of the pump, whichcustomarily is of the positive displacement, constant speed type. Thedrilling fluid is thus pumped or forced in conventional mannerdownwardly in a stream through the passage within the hollow drillstring, and is discharged from the lower end of the drill string throughsuitable holes in the drill bit, and returns to the top of the boreholethrough the annular space surrounding the drill string. At the top ofthe borehole the casing 14 is provided with a side discharge pipe 40leading to sump 36, from which sump, after settling, the drilling fluidis withdrawn for reuse as before-described. The pressure drop in thedrilling fluid stream between the pump and the holes in the drill bitprovides a pressuredifference between selected points or locations inthe drill collar, which pressure difference may be employed in a novelmanner in the system of the invention.

Referring now to Figures 2a and 2b, drill collar 20 extends downwardlyfrom drill pipe 22 to drill bit 18 and is attached to those elements byconventional threaded joints 21 and 23, respectively. Snugly fittedwithin the lower end of the smooth bore 42 of collar 20 is an instrumentspool 43 arranged to support an instrument case in a manner hereinaftermore fully described. This spool is held in fixed position in bore 42 bysuitable means, such as internal lock rings or set screws 44 threadedthrough the wall of the drill collar 20 and engaging a suitable annulargroove 44a in the exterior face of the lower flange of the instrumentspool. Sealing means, such as an elastic ring 46a mounted in a suitableannular recess 46 in the lower flange of the instrument spool 43 areemployed to seal off an annular space 47 between the drill collar andthe instru ment spool from entry of drilling fluid. At its upper endspool 43 is provided with a plurality of radially extending legs 48snugly fitting bore 42, and a smooth end face provided with an annulargroove 49 containing an annular sealing ring 49a. Situated immediatelyabove spool 43 in bore 42 of the drill collar is a lower drilling fluidpressure sensing means or device, comprising an internally recessedbarrel member 50, to the inside of which at its lower end is secured asnugly fitting internal sleeve or tube 51 provided with a number ofperforations or holes 52. Tube 51 has a smoothly surfaced exterior faceadapted to coact with respective sealing rings 53 and 54 of a suitableelastomer such as neoprene, contained in suitable internal annulargrooves in barrel member 50. The sealing rings are adapted to preventleakage of drilling fluid through the passages or holes provided for setscrews 55 which serve to secure the perforate tube 51 within the barrelmember 50. The internal configuration of barrel 50 is such as to providean internal annular groove or recess of suflicient length to span all ofthe before-mentioned holes 52 in tube 51 and thus to form, with tube 51,an elongate annular cavity 56. The exposed internal surface of tube 51is thus arranged and adapted to form a portion of the boundary of thedrilling fluid stream passage extending through the drill collarthere-adjacent, and accordingly the cavity 56 serves to sense or receivethrough holes 52 the pressure in the drilling fluid stream at that pointor location within the drill collar. The lower end of barrel member 50is provided with a smooth, radially extending end face adapted to coactwith sealing ring 49a in the before-mentioned annular groove 49 and isprovided with a similar, radially extending upper end face provided withan annular groove 57 arranged for the reception of a sealing ring 570.Barrel member 50 is preferably concentrically positioned within drillcollar 20, by means of a series of integral, radially extending legs 58and 59 arranged in circumferentially spaced-apart positions around thelower and upper end portions, respectively, of the barrel member andsnugly fitting the interior wall of bore 42 of the drill collar.

Situated in the drill collar immediately above barrel member 50 is ahydraulic apparatus-supporting spool 60 (Figure 2a) having flanged endseach carrying a series of radially extending, circumferentially spacedapart legs 61 and 62, respectively, by means of which the spool isconcentrically positioned within bore 42 of the drill collar. The lowerflange of spool 60 is provided with a smooth radial end face coactingwith the before-mentioned sealing ring 57a contained in annular groove57, and the upper end face of spool 60 is provided with an annulargroove 63 in which is seated a. sealing ring 63a, as indicated.

Situated immediately above spool 60, in bore 42 of the drill collar, isa drilling fluid flow resistance varying means or device comprising aninternally recessed barrel member 64 having secured therein a flexibleand preferably elastic member or sleeve 65 as by means of pinch rings 66and 67 secured in turn to the inside of the opposite ends of the barrelmember 64 by means of suitable screws as indicated at 67a. Barrel member64 is provided with an internal annular recess closed on its interior bysleeve 65 and providing between the exterior surface of sleeve 65 andthe interior surface of the barrel member an elongate annular space orcavity 68 for a purpose hereinafter described. The inner surface of theflexible sleeve 65 is exposed to the drilling fluid stream and forms aportion of the boundary of the drilling fluid stream flowing through thedrill collar.

Annular space 68 is effectively sealed from the drilling fluid stream bythe pinching action of pinch rings 66 and 67 on respective ends offlexible sleeve 65. Suitably secured to the internal face of pinch ring67, as by means of welded circumferentially spaced-apart radial vanes69, is a strong metal core means preferably in the form of a strongsteel tube 76 positioned preferably concentrically within and extendingthroughout the full length of the exposed portion of the interior ofsleeve 65. Tube 70 serves as a central passage to limit the degree ofclosure of the sleeve 65 and to by-pass a portion of the drilling fluidstream passing therethrough, and tube 70 is of such external diameter asto provide an annular space 71 between the exterior of tube 70 and theinterior of sleeve 65, through which another portion of the drillingfluid stream normally flows when sleeve 65 is in normal position orattitude. Barrel 64 is concentrically positioned in bore 42 of the drillcollar by means of upper and lower series of radially extending,circumferentially spacedapart legs 72 and 73, respectively, which may beformed as integral parts of the barrel and are shaped to provide a snugfit within bore 42 of the drill collar. Upper pinch ring 67 is providedwith a smooth radial end face with an annular sealing ring groove 74therein.

Situated in bore 42 immediately above the flow resistance varying deviceis an upper pressure sensing or receiving device comprising aninternally recessed or grooved barrel 75 having secured therein in snugfitting relationship a perforated metal tube 76 provided with aplurality of perforations 77 all leading laterally from the bore of thetube 76 into an annular cavity or space 78 formed between the exteriorwall of tube 76 and the interior surface of barrel 75. Tube 76 serves asa screen to exclude from connected apparatus coarse drill chips or otherforeign bodies, and is securely positioned within the interior of barrel75 in a manner similar to that previously described with respect to tube51 and barrel 50 of the lower or downstream pressure sensing device.Barrel 75 is concentrically positioned in bore 42 of the drill collar,at its lower end by a series of radially extending, circumferentiallyspaced-apart legs 79, and at its upper end by an annular flange 80formed to snugly fit within the bore 42. The lower end of barrel 75 isprovided with a smooth radial and face adapted to coact in sealingrelation with a flexible sealing ring 74a situated in the aforementionedannular groove 74. Flange 80 of barrel 75 is equipped with a peripheralgroove 81 in which is mounted an elastic sealing ring 81a adapted tocoact with the smooth wall of bore 42. The upper radial end face offlange 80 is provided with an annular recess in which is seated anelastic sealing ring 82. Sealing ring 82 is adapted to be compressed, asindicated, when drill collar 29 is screwed at threads 21 onto drill pipe22, and together with the previously mentioned sealing rings is adaptedto effectively seal the space lying between the several barrels andspools and the interior wall of the drill collar from entry of drillingfluid. Drilling fluid has access to cavity 78 through the aforementionedperforations 77, hence the device is effective to act to receive orsense the static pressure of the drilling fluid stream therewithin in amanner similar to that hereinbefore explained with reference to thelower pressure sensing or receiving device.

From the foregoing description of the structure encased within the drillcollar 20, it will be seen that there is provided a central passagethrough which the drilling fluid is forced to flow in a stream fromdrill pipe 22 to drill bit 18. It is further apparent that the upstreamressure within the drilling fluid stream at a point within tube 76 ofthe upper pressure receiving device may be determined 0 gauging the likepressure in the confined annular space or cavity 73, and that thepressure there apparent may be transmitted or translated to a distantpoint such as that within the cavity 68 for utilization at that point,by hydraulically connecting the latter with space 78 as by means of ahydraulic conduit, the pressure transmission in the preferred embodimentoccurring by actual flow or transfer of drilling fluid from space 78 tocavity 68 through the hydraulic conduit connection. The sameconsiderations apply with respect to the lower pressure receiving deviceor means, wherein the pressure of the drilling fluid in the streamwithin tube 51 is available for transmission from the annular cavity 56which communicates directly with the interior of tube 51 through holesor perforations 52. Since by reason of the inherent frictional lossesoccuring within a fluid stream flowing in a closed conduit, a pressuregradient exists along the stream, the pressure sensed at the upperpressure receiving device or means, within cavity 78, is greater thanthat in the drilling fluid stream in the annular space 71 bounded by theresilient sleeve 65, and the pressure sensed within the cavity 56 in thelower pressure sensing device or means is lower than that at either ofthe mentioned upstream points, it being noted that the drilling fluidstream flows downwardly from drill pipe 22 to bit 18 in the directionindicated by the several arrows in the drill collar.

It thus is seen that there is provided a first or upper pressure sensingor receiving device at one location or point in the drilling fluidstream, a second or lower pressure receiving means at a second locationor point, and a drilling fluid flow-changing means or device at alocation between said points, each of said pressure sensing or receivingmeans being arranged to encircle the drilling fluid stream or form aportion of the boundary thereof.

The sealed space lying outside the several spools and barrels but withinbore 42 of the drill collar is utilized to house apparatus, as will behereinafter more fully described, and is preferably filled with asuitable pressure compensating hydraulic fluid or oil, whereby therelatively high external pressure of the drilling fluid may be equalizedor neutralized. To allow the pressure of the pressure compensating fluidsurrounding the several barrels and spools to remain approximately equalat all times to that of the drilling fluid, regardless of pressure andtemperature variations in the latter, there is provided a sealedflexible bellows 34 (Figure 2a) suitably mounted on spool 60, and havingits inside communicating with the drilling fluid stream by means of atube 85.

It is evident that a considerable portion of the drilling fluid flowingthrough the drill collar will normally flow through the annular space 71between tube 70 and sleeve 65, and that this portion of the drillingfluid flow may be restricted or completely closed off by inward flexure,of sleeve 65 from the attitude or position depicted in Figure 2a. Thus,if sleeve 65 were inwardly flexed into contact with the exterior surfaceof tube 7%, the drilling fluid flow through the annular space 71 wouldbe shut off, and thus the flow restricted to that through the bore oftube 76. Any such restriction of (hi ling fluid flow is reflected in apressure rise in the drilling fluid upstream from sleeve 65. It isevident that inward flexure of sleeve 65 may be effected by applicationto the exerior surface thereof, that is, in annular cavity 63surrounding sleeve 65, of a pressure greater than that in the drillingfluid stream within the annular space 71. Thus, it is seen that if space78 in the upper pressuresensing device is hydraulically connected withthe annular cavity or space 68 surrounding sleeve 65, as by means of asuitable conduit, flow of drilling fluid will occur, from the space 78to the annular space 63, by virtue of the before-mentioned pressuredifferential therebetween, and this action will result in inward flexureor diametral contraction of sleeve 65 with the consequent creation ofboth a further pressure rise in the drilling fluid upstream from sleeve65, and a pressure drop within the sleeve 65 due to the increasedvelocity of ficw of the fluid through the thus restricted passage, whichstill further increases the before-mentioned pressure differentialbetween spaces 78 and 68.

If, following this, the annular space 68 is hydraulically connected withspace 56 of the lower pressure sensing device downstream from space 68,drilling fluid will then be exhausted from space 68 to space 56 byvirtue of the pressure differential therebetween, and thereby permitoutward flexure or diametral expansion of sleeve 65. The outward flexureof sleeve 65 is enhanced if the sleeve is formed of resilient material,such as a synthetic rubber of tough and elastic quality; hence in thepreferred embodiment of the invention, said sleeve is formed ofresilient material.

It is found that as soon as inward flexure or contraction of sleeve 65is commenced, a hydraulic action not unlike that of a Venturi meter isinitiated, in which, as the stream cross-section is reduced, thedrilling fluid velocity within the sleeve is increased with a resultantcorresponding reduction in pressure in that region, which action ishereinafter termed a venturi action. Under the influence of thedescribed action, the pressure differential between space 68 and theinterior of sleeve 65 is increased as hereinbefore mentioned and sleeve65 thus tends to continue to flex inwardly automatically and withoutfurther increase of external pressure, kinetic energy from the drillingfluid stream being absorbed or used in the flexure of sleeve 65 in theprocess. With ordinarily employed drilling fluid flow rates andpressures, the unrestrained inward flexing or contraction of sleeve 65would quickly result in a rapid, complete, inward collapse of the sleeveand complete closing of the drilling fluid passageway, and possiblyrupture of the sleeve. Such complete collapse is undesirable and is, inthe illustrated embodiment of the invention, prevented, by means such astube 70 positioned inside the sleeve, as hereinbefore described.

In the apparatus illustrated in Figures 2a and 3b, drilling fluidpressure sensed at space 78 may be controllably transferred to theexterior surface or the now restricting sleeve 65 by movement ofdrilling fluid through hydraulic tubing 9t), a preferablyelectroma-gnetically operated three-way control valve 91, and tubing 92,to cause the sleeve 65 to contract and thereby produce in the drillingfluid stream upstream therefrom a controlled pressure rise. Thishydraulic connection may be more easily traced by reference to thehydraulic circuit diagrams of Figures 3a and 3b which representschematically the hydraulic connections and other apparatus depicted inFigures 2a and 2b, and from which figures it will be evident that thenoted pressure transfer can occur only when valve 91 is actuated byenergization of its magnet or solenoid 150 as depicted in Fig. 312. Bymeans of valve 91, control over the time and extent of inward flexing ofsleeve 65 may be effected, as will be later more fully explained.

It will be noted that when inward flexing of sleeve 65 occurs, flow ofthe stream of drilling fluid therethrough is restricted, the extent ofthe restriction being limited by tube 70 and by the time period duringwhich the pressure sensed at cavity 78 is applied to the exterior ofsleeve 65. The result of any such restriction is the initiation andpropagation of a pressure rise in the drilling fluid stream above sleeve65, which pressure rise travels through the drilling fluid stream to thetop of the borehole and is there detected and recorded in a manner to bepresently explained. Pressure increases of the type thus produced areemployed for signaling, as has been previously mentioned. To make thepressure rise into a repeatable pressure-change signal, it is onlynecessary to remove the restriction imposed by sleeve 65 after a sharppressure rise has been produced, whereupon another pressure rise can beproduced. To induce return movement of the previously flexed orcontracted sleeve 65 to its normally expanded condition, it is onlynecessary to reduce the pressure outside that sleeve to a value at orbelow the pressure existing at the time in the stream within the sleeve65. This is accomplished with the pressure-change signal producingapparatus depicted in Figures 2a and 2!: by return movement of valve 91to the deenergized position indicated in Figure 3a, whereby valve 91then connects the space 68 outside of sleeve 65 through a suitableconduit means such as tubing 95, to the downstream cavity 56, wherethere exists a pressure lower than that within sleeve 65 and space 68.Drilling fluid is then exhausted from space 68 around sleeve 65 throughtubing 92, valve 91, and tubing 95, to cavity 56 from whence it returnsto the drilling fluid stream within tube 51 through the before-mentionedholes 52, thereby permitting sleeve 65 to expand to normal diameter.Return flexure of sleeve 65 to the normal attitude or diameter as justdescribed and as shown in Figures 2a and 3a is: aided, in theillustrated embodiment of the invention, by the natural elasticity ofthe sleeve 65.

From the above, it is clear that a pressure-rise signal may be initiatedand propagated in the drilling fluid stream above sleeve 65 by supplyinga pulse of electric current to the solenoid 150 of the solenoid-operatedvalve 91, the result being actuation of the valve to cause the temporaryconnection of cavity 78 to cavity 68 in turn resulting in inward flexingof sleeve 65; followed by deenergization of the solenoid and return ofvalve 91 to normal position under the influence of the valve spring asindicated in Figure 3a to connect cavity 68 to lower cavity 56, and theconsequent return of sleeve 65 to normal diameter. While there may thusbe propagated a controlled fluid pressure-change signal comprising acomplete cycle of pressure rise and fall to normal pressure, it issufficient for some purposes for only the pressure rise to bepropagated, and hence in this specification and the claims to follow,the terms flow change, pressure rise, pressure change and derivationsthereof, are intended to relate equally well to either type of pressurechange signal propagation in the fluid stream, that is, either apressure rise, a pressure decrease, a pressure rise followed by apressure drop, or a pressure drop followed by a pressure rise. Asindicated in Figures 2a, 2b, 3a and 31), electric current pulses may besupplied to the solenoid 150 of valve 91 via insulated conductors 98 and99 which extend through sealing grommets in the case of the magnetportion of valve 91 and extend on to information-obtaining apparatuscontained on the instrument spool 43 and indicated generally byreference numeral 180 in Figure 2b. Referring again to Figures 3a and3b, operation of the apparatus through successive pressure-change cycleswill be explained, it being noted that the flow of drilling fluidthrough the collar 20 is from top to bottom in those figures, asindicated by the arrows within the bores of the members there depicted,and it being noted that there is a pressure gradient along the drillingfluid stream from top to bottom thereof as shown in the drawing.Cavities 78, 68 and 56 and the tubing and valve ports and passagesinterconnecting them are assumed to be full of drilling fluid. Uponreceipt from the information obtaining apparatus 100 of a pulse ofelectric current by the solenoid of control valve 91, the valve isopened or actuated to the opened position indicated in Figure 3b topermit flow of drilling fluid from cavity 78 through tubing 90, valve91, and tubing 92 into cavity 68 under the influence of theaforementioned pressure gradient. Sleeve 65 is thereby caused to flex orcontract inwardly to a drilling fluid stream flowrestricting positionsuch as that indicated in Figure 3b. The inward flexure or contractionof sleeve 65 initiated by the action of the drilling fluid pressure thustranslated to its exterior, continues until further inward movement ofthe sleeve is prevented by tube 70, and this results, due to theresultant restriction of flow of drilling fluid therethrough, in apressure-rise in the drilling fluid upstream from the sleeve 65. Uponcessation of the pulse of electric current through the solenoid 150 ofthe valve 91, the valve returns to the position as shown in Figure 3aunder the influence of spring 149, thereby cutting off transmisssion ofpressure from the upper pressure-sensing 9 device cavity 78 to sleeve 65and connecting the space surrounding the sleeve 65 to cavity 56 of thedownstream pressure-sensing device, in which latter cavity the pressure,already below that at either sleeve 65 or the upper pressure-sensingdevice, may have been further lowered to some extent by the restrictionof flow of drilling fluid through the flow-restricting sleeve 65.Drilling fluid is then exhausted from cavity 68 through tubing 92, valve91, and tubing 95 into downstream cavity 56, and'therefrom through holes52 into the drilling fluid stream. This action is accompanied by outwardflexure or expansion of sleeve 65 to normal position. Such return ofsleeve 65 to normal position again allows unrestricted flow of drillingfluid, whereupon the pressure rise above sleeve 65 disappears, and thepressure gradient through the several parts of the apparatus againassumes a normal value.

If it is desired to limit the magnitude of the pressurerise signal to avalue less than its maximum, it is only necessary to limit the durationof each of the electric current pulses to a period insufiicient to allowcomplete inward flexure of sleeve 65 so that cavity 68 is connected tocavity 56 before complete inward flexure of sleeve 65 is accomplished.Thus, it is evident that the duration of a pressure-rise signal may beregulated by corresponding regulation of the length or duration of theelectric current pulse passed through the solenoid portion of the valve91. Hence, the apparatus may be employed to transmit information viapressure-change signals to the surface from within the borehole, usingany suitable coding system connected to the solenoid 150.

Referring to Figure 2a, the solenoid valve 91 is suitably mounted uponthe exterior surface of instrument spool 60 by means of suitable bindingbands 120 and 121 passed around the outside of the valve and encirclingthe barrel of spool 60. The hydraulic conduits or tubing 90, 92 and 95,serving to connect the two pressure-sensing devices and the drillingfluid stream flow-restricting device with valve 91, readily extendbetween those several units through spaces between the radiallyextending legs on the various barrels and the instrument spool, asindicated in Figure 2a. While in the preferred embodiment of theinvention as illustrated, the space between the interior wall of thedrill collar bore 42 and the aforementioned barrels and instrument spool68 is filled with a suitable hydraulic liquid such as oil, this spacemay conveniently be filled under certain operating conditions with asuitable solid or semi-solid medium providing any desired degree ofmechanical support for the tubing and other components. In the case ofliquid, provision is made for expansion and contraction of the liquid bybellows 84.

Referring again to Figures 1, 2a and 2b, the exterior of drill collar21} has applied thereto, as by cementing or vulcanization, a jacket orlayer 122 of rubber or other suitable material arranged to insulateelectrically a con siderable length of the drill collar. Mounted undertension upon jacket 122 and surrounding the drill collar is a ringelectrode 123 to which is secured an electric conductor 124 passingthrough an insulation grommet 125 mounted in a suitable threaded hole inthe drill collar wall and connecting electrode 123 to an internalcontact 126 mounted flush in bore 42 of the drill collar. Contact 126 isarranged for electrical coaction with a spring brush 127 suitablymounted on an insulating grommet 125 carried upon the leading into theinterior of a case 138 arranged to house the instrumentalities andconnections of the information-obtaining apparatus 100. Apparatus 100 isprovided with a ground conductor 131 passing out of case 130 through agrommet 132 electrically grounding the apparatus to the earth by way ofa grounding screw secured in a suitable hole in the lower flange ofinstrument spool 4-3 as indicated. Thus, it will be noted that bit 18and the lower exposed portion of drill collar 20, which are electricallyconnected together at their threaded juncture 23 and electricallyconnected to instrument spool 43 by metallic contact therewith, arearranged to act as a lower electrode of the information-obtainingapparatus. Ring electrode 123 forms the other electrode of theinformation-obtaining apparatus. The information-obtaining apparatus,which per se forms no part of the present invention and may beconstructed like those disclosed in the patents to Silverman 2,354,887and Arps 2,524,031, is depicted generally in Figure 2b. Theinformation-obtaining apparatus indicated generally at has output leads132a and 13212 extending to and electrically connected with aconventional two-conductor socket 138 mounted on case and into which theplug ends of the aforementioned conductors 98 and 99 are secured. Bythese means electrical current output pulses produced by theinformation-obtaining apparatus, and representing desired information,are transmitted or conveyed to the solenoid of valve 91.

Valve 91, which acts in the manner hereinbefore de scribed when suppliedwith electric current signal pulses, may be of any suitable andconventional construction. As illustrated in Figures 3a and 3b, itcomprises a nonmagnetic and smoothly bored cylindrical valve body 142provided with first, second and third spaced ports 143, 144 and 145,respectively, in which conduits 90, 92 and 95 are respectively securedin any suitable manner as, for example, by brazing. Slidably mounted inthe bore of the valve body 142 is a smoothly fitting valve core 148which is urged toward a closed or exhaust position by a compressionspring 14-9 acting between one end of the valve core and the opposedinner end wall of the valve solenoid 151) which is suitably secured tothe valve body as by being screwed thereon or press fitted and soldered,as indicated. The ferromagnetic solenoid armature 151 is secured to thevalve core 148 as by being threaded into a suitable tapped hole in thelatter and is arranged to move the valve core from the exhaust positionindicated in Figure 3a to the inlet position indicated in Figure 3b,with attendant compression of spring 149, in response to energization ofthe solenoid winding by an electric current. Valve core 148 may beprovided with annular grooves and cooperating elastic sealing rings 152,153 adjacent its ends to exclude drilling fluid from the space adjacentthe valve ends, and may be provided with a longitudinal duct 154extending from end to end thereof as indicated to provide free flow offiuid for balance of pressure on the opposite ends of the valve core. Ifdesired, this space may be filled with oil.

It will be noted from the preceding description that only suchelectrical energy as is used by the informationobtaining apparatus andthe relatively small amount used by the solenoid of valve 91 need besupplied by electric power means contained within the drill collar, therelatively large amount of power required for producing pressure-changesignals being in other than electrical form and entirely furnisheddirectly by the drilling fluid stream as before-described. Since theinformationobtaining means usually requires but a small amount ofelectric power, and the power consumption of the solenoid of the valveis intermittent and of very low value (of the order of a fraction of awatt), only a small and inexpensive battery or electric power sourceneed be carried in the drill collar. Such a small and inexpensivebattery is indicated in Figure 2b as comprising a circumferentiallyarranged series of individual cells, two of which are shown at 166 and167, electrically interconnected in suitable fashion and housed incasing 130 and supplying electric current to the informationobtainingapparatus through suitable leads 168 and 169.

Signals in the form of a pressure change, or a plurality thereof,propagated in the stream of drilling fluid in the drill collar asbefore-described, are detected at the top of the borehole by aconventional pressure transducer unit 170 shown in Figure l, whichoperates to translate pressure-change signals in the drilling fluidstream within pipe 38, to which the transducer is hydraulicallyconnected as indicated, into corresponding electric signals. Thetransducer output electric signal is applied by suitable conductors to aconventional amplifier and electrical filter unit 171 to which power issupplied from a suitable source such as a battery 172. The output of theamplifier and filter unit is fed to a conventional graphic recorder unit175 via conductors 173, 174. The recorder has a pen, indicated at 176,arranged to produce a trace 177 on a moving strip of paper 178, thetrace indicating the amplitude and duration of the variations in theelectrical signal output of unit 171, which in turn are correspondinglyindicative of the variations in pressure in pipe 38 and are thusindicative of the information obtained in the borehole. The graph paperis moved past pen 176 by a suitable mechanism including gearing housedin a case 179 forming a part of the recorder unit, which gearing may beactuated by a clockwork or as shown by a cable 180 coursing over guidepulleys 181 and 182, the cable having an end secured by suitable meansto traveling block 28 of the drilling rig. The thus generally describedelements serving to translate and log the pressure-change signalsreceived in pipe 38 in correlation with the position of bit 18 in theborehole or with respect to time are conventional and well known in theart. They may, for example, be similar to those shown and described inthe aforementioned Arps Patent No. 2,524,031.

Referring now to Figures 4, a and 5b, which depict transverse sectionalviews showing a modification of the by-pass tube '70 in the drillingfluid flow restricting device, a modified form of structure is depictedfor regulating the action and extent of the inward flexure of flexiblesleeve 65. This modification of core or tube 70 may be employed to giveextended service life to flexible sleeve 65 under extremely severeoperating conditions. The modified type of drilling fluid by-pass tubemember 70a preferably is given the form of a core of twoalobedcrosssection and having a central by-pass passage or bore 70b extendingtherethrough from end to end, and having two opposed, substantiallyplanar external faces 70c and 70d between which and the interior wall offlexible sleeve 65 is provided an outer pair of drilling fluid streamflow passages 71a, 71b, adapted to be closed or partially closed byinward flexing of sleeve 65, whereby to restrict the flow of drillingfluid to the central passage 70b and produce a pressure rise in thedrilling fluid upstream from sleeve 65. Figure 5a illustrates thismodified form of by-pass tube with sleeve 65 in the normal ornon-flowrestricting attitude, and Figure 5b illustrates across-sectional view of the modified form of by-pass tube in sleeve 65when the latter is in inwardly flexed, flow-restricting position. Itwill be noted from an examination of Figure 5b that sleeve 65, due toits thickness and its elastic nature, tends not to fully close againstcore 70a and thus leaves open a plurality of drilling fluid passages 70eadjacent each intersection of its planar faces with the curved portionsof its outer perimeter. Passages 70e permit or allow a continuous flowof drilling fluid through the interior of inwardly flexed sleeve 65,which flow eliminates any tendency toward fluttering or rapid partialopening and partial closing of sleeve 65 against tube 70a, which couldoccur under certain circumstances if complete closure of sleeve 65against core 70a were effected. Thus this form of by-pass tube may beused where it is desired to transmit long pressure-rise signals Wherefluttering might occur and where operating conditions are extremelysevere. In Figure 4 there is indicated the manner in which by-pass tube70a is secured within flexible sleeve 65. By-pass tube 71111 has itsexternal perimeter formed with the same radius as the internal radius ofpinch ring 67, and accordingly provides a snug fit between the twoelements along the curved portion of the perimeter of core 70a. Alongthe curved upper edges of the planar upper end face of core 79a, thecore is welded to the interior of pinch ring 67, as indicated in Figure4. Additionally, core a is supported in concentric position withinelastic sleeve 65 by its base or lower end resting upon a shelf 76 (Fig.4) formed by the upper end face of lower pinch ring 66, the internaldiameter of which is, for the purpose, made slightly less than that ofpinch ring 67.

Referring now to Figures 6, 7a and 7b, there is shown a modified form ofdrilling fluid by-pass tube or core means 70m having a longitudinalby-pass bore 7% therethrough end to end and having a plurality oflongitudinally extending lobes 70p, the outer surfaces of which formsegments of a circle of a diameter equal to the internal diameter ofupper pinch ring 67, and the upper ends of which lobes are brazed orwelded to the internal bore of that pinch ring as indicated in Figure 6.The external surfaces of by-pass tube 70m between the aforementionedlobes are formed with longitudinally extending, concave channels havingradii approximately equal to the internal radius of sleeve 65 and arepreferably, but not necessarily, each provided with a longitudinallyextending drilling fluid by-pass slot 70: or a plurality thereof,whereby, when sleeve 65 is flexed inwardly in contact with tube 70n, asindicated in Figure 7b, there are provided a plurality of drilling fluidflow passages between the elastic sleeve 65 and the core member therebyobviating fluttering of the flow-restricting sleeve during transmissionof long signal pulses. Since flow of drilling fluid through therestricted passage formed by. the slot 70: is at a higher velocity thanthat in the stream thereabove, the pressure is decreased which aids inholding sleeve 65 firmly against the tube. Since the external concavesurfaces of the core 70m are of a radius substantially equal to theinternal radius of the flexible sleeve 65, as beforementioned, thelatter is subjected to a minimum of distortion and stress when flexedinwardly into contact with the core member. This latter action isillustrated in the cross-sectional view of Figure 7b. Since elasticsleeve 65 is distorted but little when used in conjunction with the formof core just described, it is adapted to have a maximum service life.

From a consideration of the above description considered in conjunctionwith the drawings, it will be noted that the invention provides asimple, durable means of extracting and utilizing energy directly from amoving body of drilling fluid in a drill string in an earth wellborehole to produce one or more signaling flow resistance or pressurechanges in the fluid stream within or adjacent the bottom of the drillstring for transmission through the drilling fluid stream to the surfaceof the earth, the pressure changes being representative of desiredinformation obtained at or adjacent the lower end of the drill string.

While the aforementioned objects of the invention are accomplished bythe disclosed specific embodiments of the invention, it is apparent thatvarious modifications and variations of the described system and of itsparts may be made without departing from the invention, as defined bythe appended claims. For example, information other than that secured byelectrode means may be transmitted, it being necessary only that theinformation be supplied to the valve solenoid in the form of an electriccurrent or one or more pulses of electric current, which are significantof the information to be converted into corresponding fluid flowrestrictions. Also, variations in the form and assembly of thepressure-sensing and flow-restricting means may be effected. Forexample, the pressure-sensing means could readily take the tionship,they may, in practice, be spaced apart along the drilling fluid streamany suitable distance; and they may readily be positioned in anotherelement of the drill string rather than in the drill collar.

While in the preferred embodiment of the invention herein disclosed andexplained, a change in the resistance to flow of fluid resulting in apressure change or a flow change in the drilling fluid stream, or both,is created by contraction of a flexible tubular member encircling thedrilling fluid stream, it will be evident that the invention equallywell applies to means wherein such pressure or flow change is created byflexure of a flexible member or movement of a movable member which onlypartially encircles the drilling fluid stream or merely protrudes inproper manner into the stream, or which is itself encircled by thestream and is flexed or moved outwardly to restrict the stream toproduce a pressure rise or inwardly to create a pressure drop. Also,means producing the converse of such actions is envisioned. Accordingly,it is not desired to limit the broad aspects of the invention to thespecific details of the described embodiments thereof.

What is claimed is:

1. In a system adapted for logging boreholes while being drilled bymeans including a drill string having a fluid filled passage extendinglongitudinally therethrough and means for forcing the fluid to flow downthrough said passage in said drill string, the combination comprising: adrill string having such fluid passage; signaling means thereinincluding variable fluid flow resistance means fixed in said drillstring in the vicinity of the lower end thereof, actuatable byapplication of fluid pressure thereto to effect a variation inresistance to flow of said fluid there through to produce a flow-changesignal in fluid in said passage; sensing means to pick up pressure ofsaid fluid in said passage at a point spaced from said flow resistancemeans; control means in communication with said sensing means andactuatable to apply said pressure to and to withdraw said pressure fromsaid variable fluid flow resistance means thereby to actuate said fluidflow resistance means to vary the said resistance to flow of said fluid;and means pqnsivetaarlzxsiaalscad ins mhol to acts e said controlmeansto caiise'said variabl flow rests-answerin e in said fluid aflow-change signal representing said n sieareafiaiaea;

2. A systenr'as deflned by claim '1' in which said fluid flow resistancemeans comprises a flexible member at least partially encircling aportion of said passage and arranged to be flexed into a fluid streamflowing therethrough.

3. A system as defined in claim 1 in which said fluid flow resistancemeans comprises a resilient member at least partially encircling aportion of said passage in said drill string and arranged to be flexedinto a fluid stream flowing therethrough; and in which said controlmeans includes a valve and means including conduit means relativelyconnecting said valve with said sensing means and said variable fluidflow resistance means.

4. In a system for logging boreholes while being drilled by meansincluding a drill string having a fluid passage extending longitudinallytherethrough and means for forcing fluid to flow down through saidpassage in said drill string, the combination comprising: a drill stringhaving such fluid passage; flow-change signal producing means includingvariable fluid flow resistance means in said drill string in thevicinity of the lower end thereof actuatable by application of fluidpressure thereto to effect a change of resistance to flow of said fluidtherethrough to produce a flow-change signal in said fluid in saidpassage; sensing means to pick up pressure of said fluid in said passageat a point spaced upstream from said flow resistance means; and signalcontrol means in communication with said sensing means and actuatable toapply said pressure to and to withdraw said pressure from said variablefluid flow resistance means thereby to actuate said flow resistancemeans to increase and decrease, respectively, the said resistance toflow of said fluid, to produce a controlled flow-change signal in saidfluid.

5. In a system for logging boreholes while being drilled by meansincluding a drill string having a fluid passage extending longitudinallytherethrough and means for forcing a stream of fluid to flow downthrough said passage in said drill string, the combination comprising: adrill string having such fluid passage; signaling means includingvariable fluid flow resistance means in said drill string in thevicinity of the lower end thereof actuatable by application of fluidpressure thereto to effect a variation of resistance to flow of saidfluid therethrough to produce a flow-change signal in said stream offluid in said passage; sensing means to pick up the pressure of saidfluid in said passage at a point spaced downstream from said flowresistance means; and signal control means in communication with saidsensing means and actuatable to apply said pressure to and to withdrawsaid pressure from said variable fluid flow resistance means thereby toactuate said flow resistance means to decrease and increase,respectively, the said resistance to flow of said fluid, to produce acontrolled flow-change signal in said stream.

6. In a system for logging boreholes while being drilled by meansincluding a drill string having a fluid passage extending longitudinallytherethrough and means for forcing a stream of fluid to flow downthrough said passage in said drill string, the combination comprising: adrill string having such fluid passage; signaling means includingvariable fluid flow resistance means in said drill string in thevicinity of the lower end thereof actuatable by application of variablefluid pressure thereto to elfect a variable resistance to flow of saidfluid therethrough to produce a flow-change signal in said stream offluid in said passage; a first sensing means to pick up pressure of saidfluid in said passage at a point spaced upstream from said fluid flowresistance means, and a second sensing means to pick up pressure of saidfluid in said passage at a point downstream from said fluid flowresistance means; and signal control means in communication with saidfirst and second sensing means and actuatable to apply said pressurefrom said first sensing means to said variable fluid flow resistancemeans while said pressure from said second sensing means is removedtherefrom, and to apply said pressure from said second sensing means tosaid variable fluid flow means while said pressure from said firstsensing means is removed therefrom, thereby to actuate said fluid flowresistance means to increase and to decrease, respectively, the saidresistance to flow of said fluid, to produce a controlled flow-changesignal in said stream.

7. A system according to claim 1, including means to receive andtranslate the flow-change signal into a senseperceptible signal.

8. A system according to claim 6, including means to receive andtranslate the flow-change signal into a senseperceptible signal.

9. In a logging system for an earth borehole being drilled by meansincluding a hollow drill string having a passage through which adrilling fluid stream flows under pressure successively past upstreamand downstream points therein, and in which system information to belogged is transmitted by pressure-change signals in and through saiddrilling fluid stream, in combination: a drill string having such fluidpassage, and a drilling fluid stream therein; signaling means includinga resilient tubular member encircling the drilling fluid stream betweensaid points and effective when flexed to produce a pressure-change insaid drilling fluid stream and thereby propagate a pressure-changesignal in the drilling fluid stream; means including informationobtaining means. acting to produce an output representative of obtainedinformation; and means including pressure-change signal control meansreceiving said output, and acting in response to said output first totranslate the pressure at one of said points to the outside of saidresilient tubular member to cause flexure thereof, and thereafter actingto translate the pressure at the other of said points to the outside ofsaid resilient tubular member to induce return flexure thereof to normalposition, to propagate a pressure-change signal representative of saidobtained information in said drilling fluid stream for transmissionthereby and therethrough.

10. A system according to claim 9, including means to receive andtranslate the pressure-change signal into a sense perceptible signal.

11. A system according to claim 9, including a by-pass core means insidesaid resilient tubular member to limit inward fiexure of the latter; andmeans to receive and translate the pressure-change signal.

References Cited in the file of this patent UNITED STATES PATENTSKoppitz June 6, Hook et a1. June 17, Bryant July 11, Harrington Oct. 30,Aagaard Aug. 8, Arps Oct. 3, McFadden Feb. 26, Sausa Mar. 25, RutgersMay 27, Otis et al. Jan. 18,

FOREIGN PATENTS Great Britain July 13,

